Yes, I know this isn't a new topic. I've read through http://paizo.com/threads/rzs2mxfk?Words-of-Power and http://paizo.com/threads/rzs2p3r6?Summon-Monster-with-words-of-power-an-exp loit and I find the explanations don't quite sit well with me.
Specifically, Servitor VII - IX allow for boosting, but there's no way (currently) to cast higher than 9th level spells, and no way to lower the +3 level increase people are claiming Boost does.
(quick caveat, I'm using d20pfsrd and the prd, so if there is more information in the actual book, please let me know)
Here's why I'm not certain that Boosting Servitor has the effect people state:
When you Boost a Target word (such as Cone) you choose which version of Boost you are doing:
Cone
Level 0
Range 10 ft.
Target A wordspell with this target word affects everything in a coneshaped burst.
Boost: The range increases to 20 feet. Boosting this target word increases its level by 2.
Boost: The range increases to 40 feet. Boosting this target word increases its level by 4.
Selected has a specific entry for boosting
SELECTED
Level 0
Range close (25 ft. + 5 ft./2 levels)
A wordspell with this target word affects a single target within range. If the wordspell deals energy damage, this word creates a ray that requires a ranged touch attack to hit, or it can be used as a melee touch attack with no range (decided by the wordcaster when the wordspell is cast). If it is used as a melee touch attack and the attack misses, the wordcaster can hold the charge and try again with subsequent attacks.Boost: Instead of one target, the wordspell affects up to one target per caster level, no two of which can be more than 30 feet apart. The range increases to medium (100 ft. + 10 ft./level). If used with an effect word that deals energy damage, the wordcaster must make multiple ray attacks for each target (they cannot be made as melee touch attacks). This boosted target word increases the level of all the effect words in the spell by 3 levels.
Thus, you Boost Selected, you can affect up to one target/caster level, and the range increases from close to medium. For that, it increases the level of the word by 3.
Servitor, however, has a special effect when the target word is selected:
If the target word is boosted, a wordspell with this effect word summons 1d4+1 of the chosen creatures.
This overrides what the affect of boosting Selected normally does. Instead of "affecting up to one target per caster level" and "increasing the range to medium", it "summons 1d4+1 of the chosen creatures". Since it is different from the Boost line of Selected, it's almost like it has an additional option for boosting that ONLY works for Servitor. Since there is no level increase listed, it would appear that it is not +3 levels, and it can work for Servitor VII-IX. Just like when you boost Barrier (no level increase):
Boost: The wall is 20 feet long per caster level and up to 20 feet high. The wall can take on any shape desired by the caster, but it must remain a vertical surface.
Is this wrong? The funny thing is I had the same opinion (boosting servitor increases the level by 3) but my GM pointed out that it didn't make sense due to Servitor VII-IX.